<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<section>
    <div class="cell p-sum col-md-4" style="width:120px;"><strong
            v-text="price*sum"></strong></div>
    <div class=" col-md-4">
        <div class="input">
            <button @click="sum=sum-1" v-if="sum > 1"><i
                    aria-hidden="true" class="fa fa-minus"></i></button>
            <input style="width: 35px" type="text" v-if="sum <999" v-model="sum">
            <button @click="sum=sum+1"><i aria-hidden="true"
                                                        class="fa fa-plus"></i></button>
        </div>
    </div>
</section>

    <!--引入vue和axios-->
    <script src="https://cdn.bootcdn.net/ajax/libs/axios/0.21.1/axios.min.js"></script>
    <script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script>
    <script>
        let v = new Vue({
            el:"section",
            data:{
                price:100,
                sum:1,
            },

        })
    </script>
</body>
</html>